S. London¶

At a Glance


Antigenic Formula	`3,{10}{15}:l,v:1,6`
Serogroup	O:3,10 (E1)
NCBI Pathogen Detection	View isolates

Background Information¶

Salmonella enterica subsp. enterica serovar London (antigenic formula 3,{10}{15}:l,v:1,6) is a serovar of the O:3,10 (E₁) serogroup. Serovar London was first identified in Reading, UK, from a patient with a surname starting with "L." Since serovar Reading was already in use, this new strain was named London, derived from the patient's name. According to the European Food Safety Authority (EFSA) and European Centre for Disease Prevention and Control (ECDC), serovar London has entered the top 20 list of most frequent Salmonella serovars in Europe. Kim et al. collected a total of 1,116 environmental samples from 31 duck farms in Jeonnam Province, South Korea and found that serovar London (22.2%) was the most frequently detected Salmonella serovars. Wen et al. reported a case of serovar London infection of the skin and soft tissue of the leg and heel.

Genetic Characteristics¶

Serovar London has been found to be polyphyletic with two lineages identified. In a nosocomial outbreak associated with serovar London, Yong et al. identified the CTX-M-14-type extended-spectrum β-lactamase-producing strains. All these outbreak strains were multidrug resistant (MDR), while the other London strains reported were susceptible to multiple antibiotics, including ampicillin, suggesting the susceptible clone retained the resistance. MDR serovar London carrying bla_NDM-1 located on an IncA/C2 plasmid was reported in Singapore. A Chinese study analyzed a total of 88 representative isolates from human and food sources in Zhejiang Province, China, during 2016–2021 and revealed that all serovar London isolates were identified as ST155 (n = 62) and grouped into two divergent clusters. Compared to serovar Kentucky isolates included in this study, three virulence genes involved in Salmonella attachment were uniquely associated with serovar London isolates. Doxycycline resistance was the most common (74.2%, n = 46) in serovar London isolates, with tetracycline (71%, n = 44), ampicillin (64.5%, n = 40), and gentamicin (56.5%, n = 35) resistance also observed at high frequencies.

Animal Reservoir¶

Pigs and ducks are potential reservoirs for serovar London.

Geographical Distribution¶

According to the metadata from NCBI PD, serovar London has been reported worldwide but mainly in US, China, and UK.

Human/Animal Outbreaks¶

Year	Location	Associated source	Number of cases
2004	South Korea	Nosocomial	3
2000	South Korea	Infant formula	31

S. London¶

Background Information¶

Genetic Characteristics¶

Animal Reservoir¶

Geographical Distribution¶

Human/Animal Outbreaks¶

Border Rejections¶

Recalls¶

References¶